Field of Application
The present invention relates to technology for remote control of a control object, using wireless communication.
Description of Related Art
Technology is known for employing wireless communication in remote control of a control object, for example as described in Japanese patent publication No. 5393240, designated in the following as reference 1. With the technology of reference document 1, image data are captured and transmitted through wireless communication by a control object (a mobile object such as a vehicle) and received by a remote operation apparatus and displayed by a display section of that apparatus. An operator of the remote operation apparatus performs remote control of the control object through wireless communication, based upon the images displayed by the display section.
Such remote control may become difficult when there is a communication delay, in particular, a reception delay. In the case of reference document 1, the reception delay is the delay between the time when an information item is transmitted by the control object and the time when the item is displayed to the operator of the remote control apparatus. With the technology of reference document 1, image data received from a control object are temporarily stored in a buffer memory before being displayed by the display section. The buffer memory is used to adjust a total delay time (the sum of the reception delay time and a delay caused by temporary storage in the buffer memory). Specifically, the delay due to temporary storage in the buffer memory is adjusted such as to maintain the total delay time at a constant value, or such that the total delay time varies only gradually. In that way, abrupt variations in the image data displayed by the display section can be reduced.
However, although the technology described in reference document 1 enables variations in the displayed image data to be made more gradual, by rendering the total delay time constant or by ensuring that the total delay time varies only gradually, it has the disadvantage of making the total delay time greater than the reception delay time. This is a problem of such prior art technology, since a sufficient speed of control response is difficult to achieve.
In particular when the drive condition of the control object is changing (e.g., a direction of motion of the control object is being changed to a required direction by remote control), the communication delay may prevent accurate control.